Although there is a substantial body of literature which deals with a variety of natural and synthetic pyrroles as antibacterial and antifungal agents, the use of arylpyrroles of molluscicidal agents is distinct from the art.
Fujisawa Pharmaceutical's work with the antifungal agent pyrrolnitrin (structure shown below) was disclosed in U.S. Pat. No. 3,428,648. However, the Fujisawa structures are distinct from the compounds of the present invention, and there is no reference to insecticidal activity. ##STR1##
Certain pyrrolomycins including antibiotic SS46506A recently isolated and identified by Meiji Seika Kaisha scientists are illustrated below. The antibiotic pyrrolomycin E contains only one pyrrole ring halogen atom. While antibiotic SS46506A is specifically claimed in U.S. Pat. No. 4,495,358, there is no mention of molluscicidal activity associated with antibiotic SS46506A either in U.S. Pat. No. 4,495,358 nor in Meiji Seika Kaisha other references on pyrrolomycins. ##STR2##
Nippon Soda and Ciba Geigy have also worked in the area of pyrrole chemistry. Both gave shown that 3-aryl-4-cyano pyrroles are effective for fungicidal and bactericidal applications. Nippon Soda has disclosed 3-aryl-trihalo pyrroles as agents for the control of plant diseases. ##STR3##
Yet another reference of interest in the pyrrole art is the U.S. Pat. No. 3,963,746 which describes 4,5-dihalopyrrol-2-yl di and tri halomethyl ketones. These compounds are said to have some activity against mites, however, the reference does not disclose or suggest any molluscicidal activity.
Other references that disclose somewhat related pyrroles include the Japanese Fujisawa Pharm. Co. ltd. patent application No. J69001528-B that describes certain aryl/cyano and aryl/nitro pyrroles wherein the pyrrole is trisubstituted and the compounds are muscle relaxants. The compounds of the present invention have a tetrasubstituted pyrrole function and the compounds are molluscicidal.
The U.S. Pat. No. 4,563,472, issued Jan. 7, 1986 and assigned to Meiji Seika Kaisha ltd. describes a number of tetrazoles that are effective as anti-microbial agents. The patentees provide a broad disclosure covering certain pyrroles, imidazoles, pyrazoles, and tetrazoles. In the case of the pyrroles, substitution may be construed to include a phenyl or a 3-chloro-2-nitrophenyl group in combination with a halogen atom and a nitro group. In all cases, the structures are substituted on nitrogen by a triiodoallyl or iodopropargyl group. There are no examples of tetra-substituted pyrroles of the types included in the present case and no finding of molluscicidal activity.
A Japanese patent application No. J62098562-A, Sanyo Electric Company on May 8, 1987 describes organic semiconductors derived from reaction products of nitrogen oxides with heterocyclic compounds. Among the broad characterization of heterocyclic compounds covered i.e. furans, thiophenes and selenophenes are included, and in a broad generic sense, certain pyrroles. However, none of the pyrroles actually described in the reference are within the disclosure of the subject application and no actual example is to be found for utilizing any pyrrole of the applicant except pyrrole itself.
European patent application No. 206523 of Imperial Chemical Industries dated Dec. 30, 1986 describes a series of fungicidal 3-alkoxy-2-heterocyclylocrylic acid esters in which the heterocylic group may encompass certain substituted pyrroles However, none of the actual examples disclosed in that case include pyrrole ring substituents which come within the scope of the generic disclosure of the subject application and, furthermore, such acrylic acid-pyrrole combinations are not a part of the molluscicidal compounds described herein.
It is therefore an object of the present invention to provide methods of and compositions for the control of mollusks and particularly to methods and compositions for controlling terrestrial gastropods such as snails, slugs and aquatic or semi-aquatic mollusks such as cowries and limpets.
These and other objects will become more apparent from the detailed description of the invention set forth below.